There is a relatively high requirement for the provision of booster batteries to the market, where the booster batteries are intended only to provide a "topping up" for a vehicle battery that has been discharged to such an extent that the vehicle battery is incapable of delivering sufficient energy so as to provide cranking and thereby starting of the vehicle. Such conditions normally arise due to the fact that the operator of the vehicle has inadvertently left the lights, radio, or other energy consuming device or accessory running in the vehicle after the vehicle ignition has been turned off. In such circumstances, the only source of power to continue to maintain the lights or other devices or accessories operating is the battery of the vehicle; and in time, the battery may be significantly reduced as to its reserve capacity.
It must be recognized, however, that in order to start the vehicle there must be cranking power delivered to the starter to begin turning the engine over. Assuming that other starting conditions are correct, once an engine has been cranked or turned over for several seconds, it is capable of sustaining its own ignition and operation. At that time, the vehicle alternator will begin delivering all necessary electrical power to the vehicle and its devices and accessories, as well as to begin to recharge the vehicle battery.
It must be kept in mind, as well, that a so-called "dead" battery in a vehicle, typically a depleted battery that has developed as a consequence of, for example, having left the lights of the vehicle operating when the ignition was turned off, is not usually completely exhausted. Other such "dead" battery circumstances may occur in a battery that has degraded with age so that it is incapable of starting the vehicle at low ambient temperatures, or a battery which is nearing the end of its useful life and which has a reduced capability of "holding its charge" over long periods of time. Thus, while the battery is not "dead" there may be insufficient power capability in the vehicle battery that can be sustained for a long enough period of time for the starter relay to close and remain closed; and particularly to deliver an appropriate starting current to the starter motor and to initiate the starting operation for the internal combustion engine of the vehicle. Of course, the internal combustion engine may be a standard engine, where a spark at its spark plugs must be maintained; or it may be a diesel engine requiring a continuing glow plug activation during the starting sequence of the diesel engine.
It is important for there to be sufficient voltage provided to the electrical ignition system of the vehicle during cranking for there to be a spark--or glow plug operation--initiated and maintained within the engine. It is normally accepted that the necessary starting voltage to initiate and maintain a spark, in an ordinary vehicle having a nominal 12 volt vehicle battery, is in the order of from 6.0 to 8.4 volts.
On the other hand, it has been noted that if a battery of even small capacity and low internal resistance is connected in parallel to the vehicle battery, and that other battery--parallel designated in general as a booster battery--is sufficiently fully charged that its terminal voltage is at its rated voltage and remains at the rated voltage during a discharge operation therefrom, then energy can be transferred from the booster battery to the vehicle battery sufficiently that at least the terminal voltage of the vehicle battery may stabilize. Then, even a relatively short cranking period will be sufficient to start the vehicle, when the spark is initiated and maintained during cranking.
As noted, it is usually necessary for the starting voltage in the vehicle to be maintained at least at the level of from about at least 6.0 to 8.4 volts for the period of time that the cranking operation continues. That period of time may only be a few seconds.
Thus, a booster battery may be provided that has a relatively low capacity in itself, perhaps even as little as 2.5 Ah to 5 Ah, and a typical vehicle starting battery may have a capacity of 20 Ah to 100 Ah. Such vehicle batteries are often designated by the term "SLI", meaning that the battery may be used and has as its purposes the function of Starting, Lighting, and Ignition in the vehicle. As noted, SLI batteries may generally have a relatively high capacity, and be capable of delivering a high current--at least for the Starting and Ignition functions.
However, in general a booster battery need not be called upon to deliver very high current--the equivalent of the full current requirements of the starter motor of a vehicle--but there may be a requirement for a relatively high current to be delivered for a short period of time, while maintaining sufficient voltage that a spark can be initiated within the engine so that ignition can be maintained.
Of course, there are other alternatives to the provision of a booster battery assembly in keeping with the present invention. In the event that an owner of a vehicle notices that he has a "dead" battery and cannot start the vehicle, he could arrange for the vehicle to be towed to a garage. There, or if the owner has access to another vehicle, the "dead" battery could be boosted using jumper cables from the other vehicle, or from a similar battery often kept on a cart so as to be transportable around the garage floor. If the vehicle owner has access to a battery charger--usually a small AC operating unit that essentially trickle charges the battery over a period of at least a few hours --and he has the time, then he could recharge the battery using the charger.
Still as another alternative, the vehicle battery could be recharged from another small battery; and a small battery that is of the correct terminal voltage but incapable of delivering high current--particularly a sustained high current--could be used for such a purpose.
There is also available an SLI vehicle battery having a separate reserve battery contained in the same casing but physically and electrically isolated from the main battery The reserve battery may be connected to the main battery to function as a booster by manually closing a switch for only as long as is necessary to start the vehicle; and thereafter the switch is manually opened to electrically isolate the reserve battery from the main battery--but not from the electrical system of the car so that the reserve battery may again be recharged.
On the other hand, the purpose of the present invention is to provide a portable (as opposed simply to being transportable) booster battery assembly that is independent of the main vehicle battery, so that it is light in weight and easily used.
Thus, the present invention provides a booster battery assembly for vehicles--as well as a utility standby battery -which will immediately provide for additional energy when connected in parallel with the vehicle battery. It will be understood, of course, that the term "vehicle" not only includes cars and trucks, but can be equally applied to such installations as motors for boats--both inboard and outboard motors--motorcycles, snowmobiles, farm tractors, and, perhaps, even to small recreational aircraft and the like.
What the present invention does not provide is a battery which essentially replicates the size and capacity of the vehicle battery, because as discussed above, that replication is not necessary. Moreover, it is not the purpose of the present invention to provide a source of recharging the vehicle SLI battery over a long period of time so as to restore its cranking power.
The booster battery assembly of the present invention provides a device that has substantially equal terminal voltage to the rated voltage of the vehicle battery to be boosted, usually 6 volts or 12 volts; and of course, cables for connecting the booster battery to the vehicle battery are a portion of the booster battery assembly. Generally, for safety reasons a switch is provided which permits the connection of the booster battery to the vehicle battery to be concluded after the physical connections of the cables have been made; and generally, a fuse is provided in series with the switch to preclude unwarranted very high current drain from the booster battery per se. This precludes any short circuiting of the booster battery, in the event that it is inadvertently mishandled.
As noted, the capacity of the booster battery may be relatively low, generally in the range of from 1% to less than 25% of the ampere-hour rated capacity of the vehicle battery. In general, a booster battery assembly according to the present invention is compact and easily portable, having a weight of less than about 3.0 Kg to 5.0 Kg.
It should also be noted that the present invention provides for the booster battery to be recharged in any suitable manner. Thus, the simple expedient step of providing a battery charger intended to deliver charging energy to the booster battery from a source of alternating current electricity is obvious, and is provided for. Moreover, it is possible under certain conditions for the booster battery to be recharged from a direct current source of appropriate voltage, such as by being plugged into the cigarette lighter of a vehicle. Thus, the booster battery of the present invention may be essentially self-contained, in that it is possible to carry the booster battery assembly in the vehicle until such time as it is necessary to be used, then use it to start the vehicle, and then recharge the booster battery from the vehicle electrical system when the engine is running and therefore the alternator or other engine-driven electrical generation system in the vehicle is operating.
Obviously, suitable indicator lamps can be provided to indicate when the booster battery is connected across the terminals of the vehicle battery, and that the switch has been closed so that energy is flowing from the booster battery to the vehicle battery. Likewise, a lamp annunciator may be provided to indicate when the booster battery is being recharged. The charging lamp can be arranged so as to be illuminated, whether the booster battery is connected to an AC source charger, or a DC source.
Because the booster battery of the present invention may also be operated as a portable power pack or standby power source, means such as the cigarette lighter socket assembly from a vehicle may be provided and connected to the booster battery, generally on the side of the switch which is remote from the booster battery, so as to permit accessory items such as an emergency Work light, a spot light, a vacuum cleaner, an air compressor or the like, to be powered directly from the booster battery.
The battery that is chosen for the booster battery assembly may be selected on the basis of being one that has high power density, or it may have high energy density, or both. A battery chosen for incorporation in a booster battery assembly for the present invention is one that has low internal impedance, and exhibits a long shelf life. It should also be one that is a generally rechargeable, and if so it should be a battery that is capable of undergoing a high number of charge and discharge cycles. Suitable batteries may be chosen from the group of lead acid batteries, nickel cadmium, other nickel metal hydride batteries, nickel zinc, silver zinc, and rechargeable alkaline manganese dioxide batteries.
It is also possible, of course, for the booster battery of the present invention to be non-rechargeable and of the reserve type. In other words, it may be possible in some conditions and for certain applications such as emergency equipment, military purposes, and the like, for the booster battery to be of such a type that it will be used only once. Generally, those batteries are of the sort where the electrolyte is stored separately from the positive and negative electrodes--the plates--of the battery, and is permitted to flood the positive and negative electrodes of the battery only when it is intended to be utilized. Such batteries may be such that they might self-discharge quite quickly after they have been activated, so that their utilization must be effected shortly after the electrolyte has been permitted to flood the plates thereof.